Pararenal stent graft and methods for use

ABSTRACT

Example stent grafts and methods for placement thereof are provided. An example stent graft may include (a) a main body stent graft defining a lumen having an inlet defined at a proximal end of the main body stent graft and having an outlet defined at a distal end of the main body stent graft, (b) a visceral-vessel opening defined in a sidewall of the main body stent graft between the proximal end and the distal end of the main body stent graft, (c) a diaphragm disposed within the lumen of the main body stent graft and coupled to the main body stent graft, wherein a first renal inlet, a second renal inlet, an infrarenal inlet and a visceral inlet are defined in the diaphragm and (d) a visceral chamber defined by a sidewall coupled to the visceral inlet and to the visceral-vessel opening.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S.Provisional Patent Application Ser. No. 61/932,280, filed Jan. 28, 2014,which is hereby incorporated by reference in its entirety.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Pararenal and juxtarenal aneurysms are infrarenal aneurysms locatedwithin about 5 mm of the renal arteries that have very short necks(i.e., less than 5 mm) or that involve 2-3 visceral arteries (e.g.,right and left renal arteries and occasionally the superior mesentericartery (“SMA”)) and that extend to within about 5 mm of the SMA. Since apararenal aneurysm typically includes only a portion of the visceraltrunk of the aorta, obtaining a proximal seal between a main body stentgraft and the vascular tissue is difficult since blood flow must bemaintained to the renal arteries, the SMA and the celiac artery. Onetechnique to treat a pararenal aneurysm may involve placing bridgingstent grafts in each of the foregoing arteries via a branched ormanifold stent graft, for example. While this technique may provide asufficient proximal seal between the stent graft and the vasculature,the proximal seal may also create a new risk, namely that blood flow tothe lumbar arteries may be blocked by the proximal seal. Specifically,the lumbar arteries perfuse the spinal cord with blood, and they tend tobe concentrated in the area of the thoracic aorta above the celiacarteries in the “seal zone” for stent grafts placed and anchored in theaorta. As such, cutting off blood flow to the lumbar arteries may causea patient to become hemodynamically unstable (i.e., blood pressure istoo low to sufficiently perfuse tissues with blood) and may put apatient at risk for paraplegia.

SUMMARY

Example embodiments beneficially provide stent grafts for treatingpararenal aneurysms, for example, and methods for placing these stentgrafts. The pararenal stent graft disclosed herein provides severaladvantages over known techniques. For example, the pararenal stent graftmay permit a pararenal aneurysm to be repaired endovascularly withminimal coverage of the aorta above the celiac artery. This may beaccomplished through an indentation or scallop-shaped-hole defined atthe proximal end of the main body stent graft and arranged below thelumbar arteries upon deployment in vivo, while the remainder of theproximal end of the stent graft extends along the visceral trunk of theaorta. The proximal end of the main body stent graft may in turn besupported by a proximal sealing ring having a bi-level constructiondefining an upper portion arranged along the most proximal edge of themain body stent graft and a lower portion arranged along the indentationor scallop-shaped hole.

In addition, the pararenal stent graft may beneficially provide adiaphragm disposed within the main lumen that defines a first renalinlet, a second renal inlet, an infrarenal inlet and a visceral inlet.This arrangement may permit one or more bridging stents that may becoupled directly to these inlets or to stent grafts coupled to theseinlets. This allows the exclusion of an aneurysm distal to the main bodystent graft down through the iliac arteries, for example.

Further, in one embodiment, first and second renal artery stent graftsmay be coupled to the renal inlets of the diaphragm and may be arrangedto cross-over one another with gentle swooping paths for stenting to therenal arteries. This configuration may advantageously permitunobstructed blood flow and may minimize both the potential for kinkingof the stent grafts and for turbulent blood flow. Also, in a furtherembodiment, the first and second renal inlets may be positioned onopposite sides of the diaphragm between the sidewall of the main bodystent graft and the center of the lumen defined by the main body stentgraft. This arrangement may provide for a gentle swooping path of thefirst and second renal lumens, because free ends of the lumens may havemore space to cross to the opposite side of the main body stent graft.In an alternative embodiment, the first and second renal inlets may bepositioned in the diaphragm closer to the center of the lumen defined bythe main body stent graft. This arrangement may beneficially result in ahigher blood flow rate.

Also, in one embodiment, a visceral chamber may be defined by a sidewallcoupled to both the visceral inlet of the diaphragm and to avisceral-vessel opening defined in a sidewall of the main body stentgraft. This visceral chamber may beneficially permit native blood flowto continue to the celiac and SMA arteries. In addition, in the eventthat an aneurysm advances proximally after placement of the pararenalstent graft, the aneurysm may be repaired by a standard thoracic stentgraft that may be deployed and mate directly with the lumen of the mainbody stent graft.

Thus, in one aspect, a stent graft is provided including the features of(a) a main body stent graft defining a lumen having an inlet defined ata proximal end of the main body stent graft and having an outlet definedat a distal end of the main body stent graft, (b) a visceral-vesselopening defined in a sidewall of the main body stent graft between theproximal end and the distal end of the main body stent graft, (c) adiaphragm disposed within the lumen of the main body stent graft andcoupled to the main body stent graft, wherein a first renal inlet, asecond renal inlet, an infrarenal inlet and a visceral inlet are definedin the diaphragm and (d) a visceral chamber defined by a sidewallcoupled to the visceral inlet and to the visceral-vessel opening.

In a second aspect, a method for placement of the stent graft isprovided including the steps of (a) introducing a guidewire into anyappropriately sized arterial configuration via arterial access, (b)loading a delivery catheter containing the stent graft according to thefirst aspect onto the guidewire, (c) moving the delivery catheter alongthe guidewire and introducing the delivery catheter into theappropriately sized arterial configuration via arterial access, and (d)deploying the stent graft into the appropriately sized arterialconfiguration and/or a lumen of a previously-placed stent graft.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the stent graft according to one exampleembodiment.

FIG. 2 is a cross-sectional side view of Section A:A from FIG. 1.

FIG. 3 is a back view of the stent graft according to the exampleembodiment of FIG. 1.

FIG. 4 is a side view of the stent graft according to the exampleembodiment of FIG. 1.

FIG. 5 is a cross-sectional top view of Section B:B from FIG. 4.

FIG. 6 is a top view of the stent graft according to the exampleembodiment of FIG. 1.

DETAILED DESCRIPTION

Example stent grafts, as well as methods of placement of the stentgrafts, are described herein. Any example embodiment or featuredescribed herein is not necessarily to be construed as preferred oradvantageous over other embodiments or features. The example embodimentsdescribed herein are not meant to be limiting. It will be readilyunderstood that certain aspects of the disclosed methods can be arrangedand combined in a wide variety of different configurations, all of whichare contemplated herein.

Furthermore, the particular arrangements shown in the Figures should notbe viewed as limiting. It should be understood that other embodimentsmay include more or less of each element shown in a given Figure.Further, some of the illustrated elements may be combined or omitted.Yet further, an example embodiment may include elements that are notillustrated in the Figures.

As used herein, “about” means +/−5%.

As used herein, “pararenal” means a region adjacent to the kidney.

As used herein, “infrarenal” means situated or occurring below thekidneys.

As used herein, “visceral trunk” refers to the portion of the aortaattached to the renal arteries, superior mesenteric artery (“SMA”), andthe celiac artery.

As used herein, “proximal end” refers to the end of the main body stentgraft that will be positioned closer to a patient's heart than the“distal end” upon deployment.

As used herein, a “sealing ring” is a structure configured to apply anoutward circumferential force to create a fluid tight seal. In someembodiments, this circumferential force may be applied laterally againstthe sidewall of the main body stent graft. In other embodiments, thecircumferential force may be applied to maintain a hole or opening in asidewall of the main body stent graft both in an open condition and incontact with vasculature. A sealing ring may be circular or oval, may becontinuous or discontinuous, and/or may be contoured or have a bi-levelshape to accommodate indentations or scallop-shaped holes in thesidewall of the main body stent graft, among other possibilities. Thesealing rings may include elastic recoil material, such as nitinol, astandard sinusoidal stent structure or a straight reinforced wire, amongother possibilities.

As used herein, “passive fixation” refers to friction, interactionbetween the cloth of the grafts, radial strength of the stent and bloodpressure that holds the component stent grafts together at the site ofoverlap.

As used herein, “active fixation” refers to features coupled to a stent,graft, or stent graft that may actively engage vasculature or anotherstent graft, including hooks, bi-directional hooks, anchors, staples,bio-activated adhesive, or a combination thereof, among otherpossibilities.

As used herein, with respect to measurements, “about” means +/−5%.

As used herein, a “stent graft” is a tubular, radially-expandable devicecomprising a fluid-tight fabric supported by a stent and may be used tobridge diseased arteries. Such stent grafts and methods for theirdeployment and use are known to those of skill in the art. For example,vascular sheaths can be introduced into the patient's arteries, throughwhich items, including but not limited to, guidewires, catheters and,eventually, the stent graft, are passed.

As used herein, “stent” is typically a cylindrical frame and means anydevice or structure that adds rigidity, expansion force, or support to aprosthesis or native vasculature, while “stent graft” refers to aprosthesis comprising a stent and a graft material associated therewiththat forms a fluid-tight lumen through at least a portion of its length.For example, the stent structure may comprise coiled, mesh, zig-zag orwoven wires or a laser cut tube. A “graft” is a substantiallycylindrical liner that may be disposed on the stent's interior, exterioror both. In some embodiments, grafts may be woven as unitary structureswith multiple lumens. For example, the main body stent graft, thediaphragm, the two renal lumens, the infrarenal lumen and the visceralchamber may all be woven together as a unitary structure or otherwisejoined together to form a unitary structure. Further, when used incombination with a graft, the stent structure may further comprise aseries of spaced apart stent rings disposed along the graft. A widevariety of attachment mechanisms are available to join the stent andgraft together, including but not limited to, sutures, adhesive bonding,heat welding, and ultrasonic welding.

The stent can be made of any suitable material, including but notlimited to biocompatible metals, implantable quality stainless steelwires, nickel and titanium alloys, and biocompatible plastics attachedto a graft. Any suitable fluid tight graft material can be used. In apreferred embodiment, the graft material is a biocompatible fabric,including but not limited to woven or knitted polyester, such aspoly(ethylene terephthalate), polylactide, polyglycolide and copolymersthereof; fluorinated polymers, such as PTFE, expanded PTFE andpoly(vinylidene fluoride); polysiloxanes, including polydimethylsiloxane; and polyurethanes, including polyetherurethanes, polyurethaneureas, polyetherurethane ureas, polyurethanes containing carbonatelinkages, woven nickel-titanium and polyurethanes containing siloxanesegments. Materials that are not inherently biocompatible may besubjected to surface modifications in order to render the materialsbiocompatible. Examples of surface modifications include graftpolymerization of biocompatible polymers from the material surface,coating of the surface with a crosslinked biocompatible polymer,chemical modification with biocompatible functional groups, andimmobilization of a compatibilizing agent such as heparin or othersubstances. The graft material may also include extracellular matrixmaterials.

The covered stent grafts can be made of any suitable material, includingbut not limited topolytetrafluoroethylene (ePTFE) lined nickel-titaniumalloy stent. The stent grafts are preferably covered and flexible. Thestent grafts may contain any other suitable components, such as surfacemodifications including but not limited to covalent attachment ofheparin.

In one aspect, the invention provides a stent graft, comprising:

a main body stent graft defining a lumen having an inlet defined at aproximal end of the main body stent graft and having an outlet definedat a distal end of the main body stent graft;

a visceral-vessel opening defined in a sidewall of the main body stentgraft between the proximal end and the distal end of the main body stentgraft;

a diaphragm disposed within the lumen of the main body stent graft andcoupled to the main body stent graft, wherein a first renal inlet, asecond renal inlet, an infrarenal inlet and a visceral inlet are definedin the diaphragm; and

a visceral chamber defined by a sidewall coupled to the visceral inletand to the visceral-vessel opening.

Referring now to FIGS. 1-6, a stent graft 100 is shown including a mainbody stent graft 105 defining a lumen having an inlet 106 defined at aproximal end 107 of the main body stent graft 105 and having an outlet108 defined at a distal end 109 of the main body stent graft 105. In oneembodiment, a portion of the lumen of the main body stent graft 105arranged between the diaphragm 110 and the proximal end 107 of the mainbody stent graft 105 may have a diameter ranging from about 20 mm toabout 46 mm. In another embodiment, the main body stent graft 105 mayhave a length ranging from about 20 mm to about 80 mm extending betweenthe proximal end 107 of the main body stent graft 105 and the proximalend 116 of the visceral-vessel opening 115. In a further embodiment, themain body stent graft 105 may have a length ranging from 0 mm to about40 mm extending between the distal end 117 of the visceral-vesselopening 115 and the distal end 109 of the main body stent graft 105.

The stent graft 100 includes a diaphragm 110 disposed within the lumenof the main body stent graft 105 and coupled to the main body stentgraft 105. The diaphragm 110 defines a first renal inlet 120, a secondrenal inlet 125, an infrarenal inlet 130 and a visceral inlet 135. Thevisceral inlet may be aligned in a quadrant of the diaphragm that liesabove the visceral-vessel opening 115, discussed in more detail below,and the infrarenal inlet 130 and the first and second renal inlets 120,125 may be arranged in various configurations in the same or otherquadrants of the diaphragm 110. For example, in one embodiment, as shownin FIG. 6, the infrarenal inlet 130 and the visceral inlet 135 may bearranged on opposite sides of the diaphragm 110 with the first renalinlet 120 and the second renal inlet 125 likewise arranged on oppositesides of the diaphragm 110 between the infrarenal inlet 130 and thevisceral inlet 135. Alternatively, the first and second renal inlets120, 125 may be arranged on the same side of the diaphragm 110 betweenthe infrarenal renal inlet 130 and the visceral inlet 135. In otherembodiments, the infrarenal inlet 130 and one of the first and secondrenal inlets 120, 125 and may be arranged on opposite sides of thediaphragm 110 with the other renal inlet arranged therebetween. In afurther embodiment, the infrarenal inlet 130 and the renal inlets 120,125 may be arranged such that there is no other inlet directly oppositethe visceral inlet 135.

In one embodiment, the diaphragm 110 may be sloped or tapered in theregions surrounding these various inlets. In one embodiment, thevisceral inlet 135 may be defined as a V-shape, a half-circle having aradius ranging from about 5 mm to about 15 mm or a complete circularopening with a diameter ranging from about 8 mm to about 12 mm, amongother possibilities. In further embodiments, the first renal inlet 120,second renal inlet 125, infrarenal inlet 130 may have a substantiallycircular shape. In one embodiment, a first renal stent graft 121, asecond renal stent graft 126 and an infrarenal stent graft 131 may bedirectly coupled to the first renal inlet 120, the second renal inlet125 and the infrarenal inlet 130, respectively, in fluid-tight mannerprior to deployment of the stent graft 100. The first and second renalstent grafts 121, 126 and the infrarenal stent graft 131 each define alumen and are configured to receive extension or bridging stent graftsthat may be held in place via passive or active fixation. Thisarrangement may provide blood flow between the stent graft 100 and therenal arteries and or may provide blood flow to the infrarenal arteriesincluding, for example, the aorta and the common iliac arteries.

In various embodiments, the infrarenal lumen 131 and the renal lumens121, 126 may be straight or gradually sweeping and their distal freeends 123, 128, 133 may be freely moved to place bridging stent grafts.In one embodiment, the infrarenal lumen 131 may have a length of atleast 30 mm. In another embodiment, the length of the infrarenal lumenmay range from about 10 mm to 60 mm. An another embodiment, theinfrarenal lumen 131 may have may have a diameter ranging from about 10mm to about 25 mm. In another embodiment, the infrarenal inlet 130 mayhave a diameter ranging from about 10 mm to about 25 mm. In yet anotherembodiment, the diameter of the infrarenal inlet 130 may be larger thanthe diameter of the infrarenal lumen 131 such that a proximal end of theinfrarenal lumen 131 is tapered 132. In other embodiments, the first andsecond renal inlets 120, 125 may each have a diameter ranging from about4 mm to about 25 mm. In one embodiment, the first and second renallumens 121, 126 may each have a diameter ranging from about 4 mm toabout 12 mm. In a further embodiment, the diameter of each of the firstand second renal inlets 120, 125 may be larger than the diameter of eachof the first and second renal lumens 121, 126 such that a proximal endof each of the first and second renal lumens is tapered 122, 127.Tapering from the diaphragm inlets to the various lumens may aid withguidewire alignment and entry into the respective lumens to placeextension or bridging stents and may encourage laminar blood flow. Inanother embodiment, the first renal stent graft 121, the second renalstent graft 126 and the infrarenal stent graft 131 may be placedseparately after deployment. In this embodiment, the renal andinfrarenal stent grafts 121, 126, 131 may have flared proximal ends thatare arranged proximal of the diaphragm upon deployment.

In one embodiment, a pair of opposing helical stent structures may becoupled to and extend along the length of one or more of the first renallumen 121, the second renal lumen 126 and the infrarenal lumen 131. Thehelical stent structures may prevent elongation of the lumens. Thesehelical stent structures may be made from biocompatible materials withelastic shape memory, such as nitinol, stainless steel, plastics,polymers or any combination of such materials, among otherpossibilities.

In a further embodiment, the diaphragm 110 may have an expandable frame111. This expandable frame 111 is configured to apply an outward radialforce to the main body stent graft 105 in response to a downward forceapplied to the diaphragm 110. The downward force may be due to bloodflow, for example. In one embodiment, the diaphragm 110 may bepositioned within the lumen of the main body stent graft 105 at orbetween a proximal end 116 of the visceral-vessel opening 115 and adistal end 117 of the visceral-vessel opening 115.

The stent graft 100 also includes a visceral-vessel opening 115 definedin a sidewall 118 of the main body stent graft 105 between the proximalend 107 and the distal end 109 of the main body stent graft 105. In oneembodiment, the visceral-vessel opening 115 may have a height rangingfrom about 10 mm to about 60 mm and may have a width ranging from about5 mm to about 20 mm. In one embodiment, the visceral-vessel opening maybe wider at a proximal end than at a distal end, which may provide moregraft surface area between the visceral-vessel opening 115 and two renalopenings 170 to provide a more robust seal between the stent graft andvasculature. In another embodiment, the visceral-vessel opening 115 maybe covered with a flow-diverting material, for example, a high pickdensity braided or woven self-expanding stent material. Thisflow-diverting material may allow patency to the visceral vessels, forexample, while minimizing the degree of unstented aortic wall to aid inanchoring the pararenal stent graft within vasculature. This may providea more robust seal between the stent graft and aorta. The flow-divertingmaterial may also permit formation of thrombus and arterial developmenttherethrough, which may aid in appropriate blood flow and blood pressurethrough this region of the main body stent graft 105.

In addition, the stent graft 100 includes a visceral chamber 140 definedby a sidewall 141 coupled to the visceral inlet and to thevisceral-vessel opening. The visceral chamber 140 may provide blood flowto the SMA and celiac arteries. In addition, a surgeon may utilize thevisceral chamber 140 to place bridging stents in the SMA and/or celiacarteries

In one embodiment, the stent graft 100 may further include a pluralityof sealing rings coupled to the main body stent graft 105. In anotherembodiment, the plurality of sealing rings may include a proximalsealing ring 145 coupled to the main body stent graft 105 at or directlyadjacent to the proximal end 107 of the main body stent graft 105. In afurther embodiment, the proximal sealing ring 145 may have a bi-levelconstruction defining an upper portion 146 and a lower portion 147. Thelower portion 147 of the proximal sealing ring 145 may be aligned withand arranged proximal to the visceral-vessel opening 115, and the lowerportion 147 may be arranged distal to the upper portion 146 of theproximal sealing ring 145. In one embodiment, the upper portion 146 ofthe proximal sealing ring 145 may be longitudinally spaced apart fromthe lower portion 147 along the main body stent graft 105 by a distanceranging from about 0 mm to about 40 mm. In the bi-level embodiment, aperipheral edge 104 of the proximal end 107 of the main body stent graft105 may have the same bi-level contour as the proximal sealing ring 145.In one embodiment, the main body stent graft 105 may have a lengthranging from about 0 mm to about 20 mm extending between the lowerportion 147 of the proximal sealing ring 145 of the main body stentgraft 105 and the proximal end 116 of the visceral-vessel opening 115.

The graft material of the main body stent graft 105 may have the sameboundary as the proximal sealing ring 145 to avoid covering the lumbararteries that deliver blood to the spine. In other embodiments, thegraft material may have a uniform circumference along the upper boundaryof the proximal sealing ring 145. In still further embodiments, thegraft material may extend beyond the upper proximal boundary of theproximal sealing ring 145 to the top or proximal edge of a fixationstent 150.

In another embodiment, the plurality of sealing rings may include avisceral-vessel sealing ring 155 coupled to the main body stent graft105 such that the visceral-vessel sealing ring 155 surrounds thevisceral-vessel opening 115. For example, the visceral-vessel sealingring 155 may apply a circumferential force to keep the visceral-vesselopening 115 intact upon deployment providing a fluid tight seal aboutthe SMA and celiac arteries. The plurality of sealing rings may alsoinclude at least one support sealing ring 160 coupled to the main bodystent graft 105 such that a first end 161 of the at least one supportsealing ring 160 is coupled to a first side of the visceral-vesselsealing ring 155 and a second end 162 of the at least one supportsealing ring 155 is coupled to a second side of the visceral-vesselsealing ring 155. The visceral-vessel sealing ring 155 may also work incombination with the support sealing ring 160 to provide acircumferential radial force relative to the main body stent graft 105to provide a fluid tight seal with the aorta, for example. In a furtherembodiment, the at least one support sealing ring 160 may include aproximal support sealing ring 163, a distal support sealing ring 164 anda central support sealing ring 160. In one embodiment, the centralsupport sealing ring 160 may be coupled to the visceral vessel sealingring 155. The proximal support sealing ring 163 may be coupled to themain body stent graft 105 between the proximal end 107 of the main bodystent graft 105 and the central support sealing ring 160. And the distalsupport sealing ring 164 may be coupled to the main body stent graft 105between the distal end 109 of the main body stent graft 105 and thecentral support sealing ring 160.

In still another embodiment, the plurality of sealing rings may includea distal sealing ring 165 coupled to the main body stent graft 105 at ordirectly adjacent to the distal end 109 of the main body stent graft105. In one embodiment, two renal openings 170 may be defined in thesidewall 118 of the main body stent graft 105 distal to the diaphragm110. In one embodiment, the distal sealing ring 165 may have two radialportions 166 joined by two arch portions 167. The two arch portions 167may be arranged longitudinally along the sidewall 118 of the main bodystent graft 105 and the two radial portions 166 are arranged about thecircumference of the main body stent graft 105. The two arch portions167 are aligned with the two renal openings 170. In one embodiment, aneffective diameter extending between the two radial portions 166 of thedistal sealing ring 165 may range from about 20 mm to about 50 mm. Inone embodiment, the two arch portions 167 may have a width ranging fromabout 4 mm to about 30 mm. In an embodiment in which renal openings 170are not provided in the sidewall 118 of the main body stent graft 105,the length of the main body stent graft 105 may be shortened to permitthe renal stent grafts to exit from the distal end 109 such that theyare able to have a gentle sweep or large radius of curvature from therenal inlet and the target vessel ostium when bridging stents areplaced.

In one embodiment, a bridging stent graft may comprise spaced-apartstent rings coupled to two wires longitudinally disposed along thelength of and on opposite sides of the bridging stent graft. Thisarrangement may beneficially prevent elongation of the bridging stentgraft. A 30 mm overlap with the renal stent grafts 121, 126 orinfrarenal stent grafts 131 may be adequate to achieve passive fixationwith a bridging stent graft during stent graft debranching procedures.The length of this overlap region may be less if active fixationfeatures are also employed with the stent grafts, for example.

The stent grafts of the present invention may contain any furthersuitable components, including but not limited to radiopaque markers toaid in visualization and to facilitate accurate placement of the stentgraft. These radiopaque markers may take the form of gold bands at thedistal end of each individual lumen of a given stent graft or adirectional marker, for example in the shape of an “S” or any othersuitable form for indicating direction and orientation of the stentgraft. In one embodiment, the proximal end 107 of the main body stentgraft 105 may be coupled to a fixation stent 150. In addition,bi-directional anchoring hooks may be formed as part of the fixationstent 150 may be utilized to gain solid purchase in the non-diseasedportion of a vessel wall. This fixation stent 150 may provide forradial-force fixation within the vessel in conjunction withbidirectional hooks. In another embodiment, the fixation stent 150 maybe biased away from the lumen of the main body stent graft 105 tomaintain fixation with vasculature in a deployed condition even if ananeurysm advances proximally.

In a second aspect, the invention provides a method for placement of thestent graft 100 according to the first aspect of the invention. Themethod includes (a) introducing a guidewire into any appropriately sizedarterial configuration via arterial access, (b) loading a deliverycatheter containing the stent graft of any of the foregoing embodimentsonto the guidewire, (c) moving the delivery catheter along the guidewireand introducing the delivery catheter into the appropriately sizedarterial configuration via arterial access and (d) deploying the stentgraft into the appropriately sized arterial configuration and/or a lumenof a previously-placed stent graft.

In one embodiment, the second aspect may further include (e) loading asecond delivery catheter containing a bridging stent graft onto theguidewire, (f) moving the second delivery catheter along the guidewireand introducing the second delivery catheter into the proximal end 107of main body lumen of the stent graft 105 via arterial access, (g)selecting from among the first renal inlet 120, the second renal inlet125, the infrarenal inlet 130 or the visceral inlet 135 defined in thediaphragm 110, (h) introducing the second delivery catheter into theselected inlet and into either a lumen 121, 126, 131 coupled to theselected inlet or an appropriately sized arterial lumen and (i)deploying all or a portion of the bridging stent graft into the selectedinlet or the appropriately sized arterial lumen.

The above detailed description describes various features and functionsof the disclosed stent grafts and methods for placement of the stentgrafts with reference to the accompanying figures. While various aspectsand embodiments have been disclosed herein, other aspects andembodiments will be apparent to those skilled in the art. The variousaspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

The invention claimed is:
 1. A stent graft, comprising: a main body stent graft defining a lumen having an inlet defined at a proximal end of the main body stent graft and having an outlet defined at a distal end of the main body stent graft; a visceral-vessel opening defined in a sidewall of the main body stent graft between the proximal end and the distal end of the main body stent graft; a diaphragm disposed within the lumen of the main body stent graft and coupled to the main body stent graft, wherein a first renal inlet, a second renal inlet, an infrarenal inlet and a visceral inlet are defined in the diaphragm; and a visceral chamber defined by a sidewall coupled to the visceral inlet and to the visceral-vessel opening.
 2. The stent graft of claim 1, further comprising a plurality of sealing rings coupled to the main body stent graft.
 3. The stent graft of claim 2, wherein the plurality of sealing rings includes a proximal sealing ring coupled to the main body stent graft at or directly adjacent to the proximal end of the main body stent graft.
 4. The stent graft of claim 3, wherein the proximal sealing ring has a bi-level construction defining an upper portion and a lower portion, wherein the lower portion of the proximal sealing ring is aligned with and arranged proximal to the visceral-vessel opening, wherein the lower portion of the proximal sealing ring is arranged distal to the upper portion of the proximal sealing ring and wherein a peripheral edge of the proximal end of the main body stent graft has the same contour as the proximal sealing ring.
 5. The stent graft of claim 2, wherein the plurality of sealing rings includes a visceral-vessel sealing ring coupled to the main body stent graft such that the visceral-vessel sealing ring surrounds the visceral-vessel opening, and wherein the plurality of sealing rings includes at least one support sealing ring coupled to the main body stent graft such that a first end of the at least one support sealing ring is coupled to a first side of the visceral-vessel sealing ring and a second end of the at least one support sealing ring is coupled to a second side of the visceral-vessel sealing ring.
 6. The stent graft of claim 5, wherein the at least one support sealing ring includes a proximal support sealing ring, a distal support sealing ring and a central support sealing ring, wherein the central support sealing ring is coupled to the visceral vessel sealing ring, wherein the proximal support sealing ring is coupled to the main body stent graft between the proximal end of the main body stent graft and the central support sealing ring, and wherein the distal support sealing ring is coupled to the main body stent graft between the distal end of the main body stent graft and the central support sealing ring.
 7. The stent graft of claim 2, wherein the plurality of sealing rings includes a distal sealing ring coupled to the main body stent graft at or directly adjacent to the distal end of the main body stent graft.
 8. The stent graft of claim 1, wherein two renal openings are defined in the sidewall of the main body stent graft distal to the diaphragm.
 9. The stent graft of claim 8, wherein the distal sealing ring has two radial portions joined by two arch portions, wherein the two arch portions are arranged longitudinally along the sidewall of the main body stent graft and the two radial portions are arranged about the circumference of the main body stent graft, and wherein the two arch portions are aligned with the two renal openings.
 10. The stent graft of claim 9, further comprising: a first renal stent graft coupled to the first renal inlet, wherein the first renal stent graft defines a lumen; a second renal stent graft coupled to the second renal inlet, wherein the second renal stent graft defines a lumen; and an infrarenal stent graft coupled to the infrarenal inlet, wherein the infrarenal stent graft defines a lumen.
 11. The stent graft of claim 10, wherein a pair of opposing helical stent structures are coupled to one or more of the first renal lumen, the second renal lumen and the infrarenal lumen.
 12. The stent graft of claim 1, wherein the diaphragm has an expandable frame, wherein the expandable frame is configured to apply an outward radial force to the main body stent graft.
 13. The stent graft of claim 1, wherein the proximal end of the main body stent graft is coupled to a fixation stent.
 14. The stent graft of claim 1, wherein a portion of the lumen of the main body stent graft arranged between the diaphragm and the proximal end of the main body stent graft has a diameter ranging from about 20 mm to about 46 mm.
 15. The stent graft of claim 9, wherein an effective diameter extending between the two radial portions of the distal sealing ring ranges from about 20 mm to about 50 mm.
 16. The stent graft of claim 1, wherein the diaphragm is positioned within the lumen of the main body stent graft at or between a proximal end of the visceral-vessel opening and a distal end of the visceral-vessel opening.
 17. The stent graft of claim 10, wherein the infrarenal lumen has a length of at least 30 mm.
 18. The stent graft of claim 1, wherein the infrarenal inlet has a diameter ranging from about 10 mm to about 25 mm.
 19. The stent graft of claim 10, wherein the infrarenal lumen has a diameter ranging from about 10 mm to about 25 mm.
 20. The stent graft of claim 10, wherein the diameter of the infrarenal inlet is larger than the diameter of the infrarenal lumen, wherein a proximal end of the infrarenal lumen is tapered.
 21. The stent graft of claim 1, wherein the first and second renal inlets each have a diameter ranging from about 4 mm to about 25 mm.
 22. The stent graft of claim 10, wherein the first and second renal lumens each have a diameter ranging from about 4 mm to about 12 mm.
 23. The stent graft of claim 10, wherein the diameter of each of the first and second renal inlets is larger than the diameter of each of the first and second renal lumens, wherein a proximal end of each of the first and second renal lumens is tapered.
 24. The stent graft of claim 1, wherein the visceral-vessel opening has a height ranging from about 10 mm to about 60 mm and a width ranging from about 5 mm to about 20 mm.
 25. The stent graft of claim 1, wherein the visceral inlet is defined as a V-shape, a half-circle having a radius ranging from about 5 mm to about 15 mm or a complete circular opening with a diameter ranging from about 8 mm to about 12 mm.
 26. The stent graft of claim 1, wherein the visceral-vessel opening is wider at a proximal end than at a distal end.
 27. A method for placement of a stent graft, the method comprising: introducing a guidewire into any appropriately sized arterial configuration via arterial access; loading a delivery catheter containing the stent graft of claim 1 onto the guidewire; moving the delivery catheter along the guidewire and introducing the delivery catheter into the appropriately sized arterial configuration via arterial access; and deploying the stent graft into the appropriately sized arterial configuration and/or a lumen of a previously-placed stent graft.
 28. The method of claim 27, further comprising: loading a second delivery catheter containing a bridging stent graft onto the guidewire; moving the second delivery catheter along the guidewire and introducing the second delivery catheter into the proximal end of main body lumen of the stent graft via arterial access; selecting from among a first renal inlet, a second renal inlet, an infrarenal inlet or a visceral inlet defined in a diaphragm; introducing the second delivery catheter into the selected inlet and into either a lumen coupled to the selected inlet or an appropriately sized arterial lumen; and deploying all or a portion of the bridging stent graft into the selected inlet or the appropriately sized arterial lumen. 